Spectrally sensitized electrophotographic materials and processes

ABSTRACT

ORGANIC PHOTOCONDUCTORS ARE SPECTRALLY SENSITIZED WITH A QUATERNATED MEROCYANINE DYE CONTAINING A 2-ISOZAZOLIN5-ONE NUCLEUS, A 2-PYRAZOLIN-5-ONE NUCLEUS, OR A COMPLEX FUSED PYRIMIDINEDIONE NUCLEUS.

United States Patent once 3,565,615 Patented Feb. 23, 1971 3,565,615 SPECTRALLY SENSITIZED ELECTROPHOTO- GRAPHIC MATERIALS AND PROCESSES Leslie G. S. Brooker and Frank G. Webster, Rochester,

N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Apr. 24, 1968, Ser. No. 723,917

Int. Cl. C03g 5/06 U.S. Cl. 961.6 25 Claims ABSTRACT OF THE DISCLOSURE Organic photoconductors are spectrally sensitized with a quaternated merocyanine dye containing a 2-isozazolin- 5'-one nucleus, at Z-pyrazolin-S-one nucleus, or a complex fused pyrimidinedione nucleus.

This invention relates to electrophotography, and more particularly to materials and elements useful in the electrophotographic process.

Elements useful in the electrophotographic process commonly comprise an electrically conductive support bearing a stratum including a photoconductive insulating layer which has a resistivity substantially greater in the dark than in light actinic thereto. Such elements can be used in electrophotographic processes, for example, by first adapting the element in the dark to obtain a uniformly high resistivity in the photoconductive insulating layer, and electrostatically charging the element in the dark to obtain a relatively high potential which may be either negative or positive in polarity. The element can then be exposed to a light pattern which lowers the resistivity and thereby the charge density of the illuminated areas imagewise in proportion to the intensity of illumination incident upon each point of the illuminated areas. A latent electrostatic image is obtained. Visible images can be formed from the latent electrostatic image in any convenient manner, such as by dusting with a finely divided, fusible pigment the particles of which hear an electrostatic charge opposite that remaining on the surface of the photoconductive insulating layer. Thereafter, the pigment particles can be fused to the surface to provide a permanent image.

Various photoconductive substances have been employed in photographic elements and processes of the type described above. Typical inorganic photoconductive materials include selenium and zinc oxide. Such inorganic photoconductive materials have inherent disadvantages, such as an inability to be readily adapted to reflex copying systems, or to produce images on transparent supports except by indirect means. Organic photoconductors avoid such disadvantages, but, generally have relatively poor sensitivity to visible radiation. It has been proposed to increase the spectral sensitivity of organic photoconductors with certain cyanine or merocyanine dyes, for example, such as listed in Table D hereinafter. The spectral sensitivity imparted by such dyes has been very weak. It therefore appears highly desirable to provide effective spectral sensitizers for organic photoconductors.

One object of this invention is to provide novel sensitized organic photoconductors.

Another object of this invention is to provide novel spectrally sensitized organic photoconductor materials.

Still another object of this invention is to provide novel compositions of matter comprising organic photoconductors and certain spectral sensitizers.

A further object of this invention is to provide novel compositions of matter comprising organic photoconductor, binder and certain spectral sensitizers for the organic photoconductor. 7

Still another object of this invention is to provide a novel electrophotographic material including a conductive support having coated thereon an insulating layer containing spectrally sensitized organic photoconductor.

A further object of this invention is to provide methods for spectrally sensitizing organic photoconductors.

Still other objects of this invention will be apparent from the following disclosure and the appended claims.

In accordance with one embodiment of this invention, novel compositions of matter are provided comprising organic photoconductors spectrally sensitized with the dyes defined more fully below. These compositions can be incorporated in a suitable binder and coated on a conductive support for use in electrophotography.

In another embodiment of this invention, compositions of matter are provided comprising organic photoconductors spectrally sensitized with the dyes described below, dispersed in an insulating binder. These compositions of matter can be coated on a conductive support and used in electrophotographic processes.

In still another embodiment of this invention, electrophotographic materials are provided comprising a conductive support having coated thereon a layer comprising an insulating binder, an organic photoconductor and a spectral sensitizing quantity of a dye defined more fully below.

In another embodiment of this invention, a method is provided for spectrally sensitizing organic photoconductors which comprises mixing a dye of the type described below with an organic photoconductor, in a concentration sufficient to effectively spectrally sensitize the organic photoconductor. Preferably, the dye and organic photoconductor are mixed in a suitable solvent.

The spectral sensitizing dyes which are employed in this invention are certain quaternated merocyanine dyes containing certain 2-isoxazolin-5-one, or 2-pyrazolin-5-one, or complex fused pyrimidinedione nuclei which, when incorporated in a test negative gelatin silver bromoiodide emulsion consisting of 99.35 mole percent bromide and .65 mole percent iodide, at a concentration of 0.2 millimole of dye per mole of silver halide, desensitize the emulsion more than 0.4 log B when the test emulsion is coated on a support, exposed through a step wedge in a sensitometer (to obtain D to light having a wavelength of 365 mm., processed for three minutes at 20 C. in Kodak Developer D-l9, and is fixed, washed and dried. As used herein and in the appended claims, the test negative silver bromoiodide emulsions are prepared as follows:

In a container with temperature control is put a solution with the following composition:

Potassium bromide165 g. Potassium iodide-5 g. Gelating. Water--1700 cc.

And in another container is put a filtered solution consisting of:

Silver nitrate-200 g. Water2000 cc.

Solution A is kept at a temperature of 54 C. during precipitation and ripening, while solution B is put in a separation funnel at a temperature of 54 C. The silver nitrate solution runs from the separating funnel through a calibrated nozzle into the container, the contents of which are kept in constant motion during precipitation and ripening, and later during finishing, by a mechanical stirrer. The precipitation is conducted over a period of 10 minutes.

The developer employed in the test referred to above is Kodak developer D-l9 which has the following composition:

G. N-methyl-p-aminophenol sulfate 2.0 Sodium sulfite, desiccated 90.0 Hydroquinone 8.0 Sodium carbonate, monohydrated 52.5 Potassium bromide 5.0

Water to make 1.0 liter.

As indicated above, the quaternated merocyanine dyes employed in this invention desensitize conventional negative silver halide emulsions. Such emulsions are inherently sensitive to blue radiation. The present dyes reduce that sensitivity. In addition, these dyes fail to provide practical spectral sensitization for such emulsions. Therefore, it was quite unexpected to find that they spectrally sensitized organic photoconductors.

Another characteristic of the quaternated merocyanine dyes of this invention is that they are substantially nonphotoconductive. The term substantially non-photoconductive as used herein means that no image is formed when a solution of 0.002 g. of the dye and 0.5 g. of polyester binder (described in Examples 1 to 6 below) are dissolved in 5.0 ml. of methylene chloride, and is coated and tested (in the absence of any photoconductor) as described in Examples 1 to 6 below.

The quaternated merocyanine dyes of this invention increase the speed of organic photoconductors by extending or increasing the response of the photoconductor to visible radiation (i.e., radiation in the range of about 400 nm. to 700 nm.). In the concentrations used, the dyes herein appear to function as spectral sensitizers when employed with efficient organic photoconductors. When the organic photoconductor used is poor or inefficient, the dyes seem to function as speed increasing compounds as well as spectral sensitizers.

The quaternized merocyanine dyes that are useful in practicing the invention include those comprising first and second 5- to 6-membered nitrogen containing heterocyclic nuclei joined together by a methane linkage; said first nucleus being selected from a 2-isoxazolin-5-0ne nucleus joined at the 4-carbon atom thereof to said linkage, a 2 pyrazolin-S-one nucleus joined at the 4-carbon atom thereof to said linkage, or a complex fused pyrimidine dione nucleus joined at the 3-carbon atom thereof to said linkage; and said second nucleus being of the type used in cyanine dyes, preferably an electron-accepting nucleus, joined at a carbon atom thereof to said linkage, to complete said quaternated merocyanine dye. The complex fused pyrimidinedione nuclei employed in the dyes of this invention feature a fused nucleus attached at one nitrogen atom and the Z-carbon atom of the pyrimidinedione nucleus. The fused nucleus can be a cyclic nucleus, such as a heterocyclic ring.

The preferred highly useful class of the quaternated merocyanine dye compounds of the invention include those represented by one of the following general formulas:

4t wherein n and ml each represents-a positive integer of from 1 to 2; L represents a methane linkage, e.g., CH=, C(CH -(C H etc.; R and R eaeh represents an alkyl group, including substituted alkyl (preferably a lower alkyl containing from 1 to 4 carbon atoms), e.g., methyl, ethyl, propyl, isopropyl, butyl, hexyl, cyclohexyl, decyl, dodecyl, etc., and substituted alkyl groups (preferably a substituted lower alkyl containing from 1 to 4 carbon atoms) such as a hydroxyalkyl group, e.g., fi-hydroxyethyl, w-hydroxybutyl, etc., an alkoxyalkyl group, e.g., B-methoxyethyl, w-butoxybutyl, etc., a carboxyalkyl group e.g., fi-carboxyethyl, w-carboxybutyl, etc., a sulfoalkyl group, e.g., ,B-sulfoethyl, w-sulfo'butyl, etc., a sulfatoalkyl group, e.g., fi-sulfatoethyl, w-sulfatobutyl, etc., an acyloxyalkyl group, e.g., fl-acetoxyethyl, 'y-acetoxypropyl, w-butyryloxybutyl, etc., an alkoxycarbonylalkyl group, e.g., ,B-methoxycarbonylethyl, w-ethoxycarbonylbutyl, etc., or an aralkyl group, e.g., benzyl, phenethyl, etc., and the like; an alkenyl group, e.g., allyl, l-propenyl, Z-butenyl, etc., and the like; R represents hydrogen, or an alkyl group (preferably a lower alkyl containing 1 to 4 carbon atoms), e.g., methyl, ethyl, propyl, isopropyl, butyl, etc.; R and R each represents an alkyl group (preferably containing from 1 to 4 carbon atoms), e.g., methyl, ethyl, propyl, isopropyl, butyl, etc., or an aryl group, e.g., phenyl, tolyl, xylyl, naphthyl, methoxyphenyl, cyanophenyl, nitrophenyl, chlorophenyl, 2,5-dichlorophenyl, 2,4,6-trichlorophenyl, etc., X represents an acid anion, e.g., chloride, bromide, iodide, thiocyanate, sulfamate, perchlorate, p-toluenesulfonate, methyl sulfate, ethyl sulfate, etc.; Z represents the non-metallic atoms necessary to complete a sensitizing or, preferably, an electron-accepting heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, which nucleus may contain a second hetero atom such as oxygen, sulfur, selenium or nitrogen, such as the following nuclei: a thiazole nucleus, e.g., thiazole, 4-methylthiazole, 4-phenylthiazole, S-methylthiazole, S-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4 (2 thienyl)thiazole, benzothiazole, 4-chlorobenzothiazole, 4 or S-nitrobenzothiazole, S-chlorobenzothiazole, 6-chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole, S-methylbenzothiazole, 6 methylbenzothiazole, 6 nitrobenzothiazole, S-bromobenzothiazole, 6-bromobenzothiazole, 5 chloro 6 -nitrobenzothiazole, 4-phenylbenzothiazole, 4 methoxybenzothiazole, 5 methoxybenzothiazole, 6- methoxybenzothiazole, 5-iodobenzothiazole, 6-iodobenz0- thiazole, 4ethoxybenzothiazole, S-ethoxybenzothiazole, tetrahydrobenzothiazole, 5,6-dimethoxybenzothiazole, 5, 6-dioxymethylenebenzothiazole, S-hydroxybenzothiazole, 6-hydroxybenzothiazole, naphtho[2,1-d] thiazole, naphtho[1,2-d]thiazole, naphtho[2,3-d]thiazole, 5 methoxynaphtho [2,3 -d] thiazole, 5 -ethoxynaphtho 1,2-d thiazole, 8 methoxynaphtho[2,1-d]thiazole, 7 methoxynaphtho [2,1-d]thiazole, 4-methoxythianaphtheno 7,6,4,5 thiazole, nitro substituted naphthothiazoles, etc.; an oxazole nucleus, e.g., 4-methyloxazole, 4-nitro-oxazole, S-methyloxazole, 4-phenyloxazole, 4,5-diphenyloxazole, 4-ethyloxazole, 4,5-dimethyloxazole, S-phenyloxazole, benzoxazole, 5-chlorobenzoxazole, S-methylbenzoxazole, 5-phenylbenzoxazole, 5- or 6-nitrobenz0xazole, S-chloro-o-nitrobenzoxazole, 6-methylbenzoxazole, 5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, S-methoxybenzoxazole, S-ethoxybenzoxazole, S-chlorobenzoxazole, 6 methoxybenzoxazole, S-hydroxybenzoxazole, -hydroxybenzoxazole, naphtho[2,l-d]oxazole, naphtho[1,2-d]oxazole, nitro substituted naphthoxazoles, etc.; a selenazole nucleus, e.g., 4-methylselenazole, 4-nitroselenazole, 4-phenylselenazole, benzoselenazole, 5-chlorobenzoselenazole, S-methoxyselenazole, S-hydroxybenzoselenazole, 5- or 6-nitrobenzoselenazole, 5 chloro 6 nitrobenzoselenazole, tetrahydrobenzoselenazole, naphtho [2,1-d] selenazole, naphtho[l,2 d]selenazole, nitro substituted naphthoselenazoles, etc.; a thiazoline nucleus, e.g., thiazoline, 4-methylthiazoline, 4-nitrothiazoline, etc.; a pyridine nucleus, e.g., Z-pyridine, S-methyI-Z-pyridine, 4-pyridine, 3-methyl-4-pyridine, 4-pyridine, 3-methyl-4-pyridine, nitro substituted pyridines, etc.; a quonoline nucleus, e.g., 2-quinoline, 3-methyl 2 quinoline, -ethyl-2-quinoline, 6-chloro-2-quinoline, 6-nitro 2 quinoline, 8-chloro-2- quinoline, 6-methoxy-2-quinoline, 8-eth0xy-2-quinoline, 8-hydroxy-2-quinoline, 4-quinoline, 6-methoxy-4-quinoline, 6-nitro-4-quinoline, 7-methyl-4-quinoline, 8-chloro- 4quinoline, l-isoquinoline, 6-nitro-l-isoquinoline, 3,4-dihydro-l-isoquinoline, 3-isoquinoline, etc.; a 3,3-dialkylindolenine nucleus, preferably having a nitro or cyano substituent e.g., 3,3-dimethyl-5 or 6-nitroindo1enine, 3,3-dimethyl-5- or 6-cyano indolenine, etc.; and, an imidazole nucleus e.g., imidazole, l-alkylimidazole, l-alkyl- 4-phenylimidazole, 1-alky1-4,S-dimethylimidazole, benzimidazole, l-alkylbenzimidazole, 1-aryl-5,6-dichlorobenzimidazole, 1-alkyl-naphtho[ 1,2-d] imidazole, l-aryl-naphtho[1,2-d]imidazole, 1 alkyl-5-methoxy-naphtho[1,2-d] imidazole, or, an -l H-imidazo[4,5-b]quinoxaline nucleus, e.g., 1,3-dialkyl-1H-imidazo[4,5-b]quinoxaline such as 1,3-diethyl-1H-imidazo[4,5-b]quinoxaline, 6 chloro-l,3- diethyl-1H-imidazo[4,5-b]quinoxaline, etc., 1,3-dialkenyl- 1H-imidazo[4,5-b]quinoxaline such as 1,3-diallyl-1H- imidazo[4,5-b]quinoxaline, 6 chloro 1,3 diallyl-lH- imidazo[4,5-b]quinoxaline, etc., 1,3-diaryl-1H-imidazo- [4,5-b]quinoxaline such as 6,7-dichloro-1,3-diphenyl-1H- imidazo[4,5-b]quinoxaline, 1,3 phenyl 1H imidazo- [4,5-b]quinoxa1ine, 6-chloro-1,3-diphenyl 1H imidazo- [4,5-b]quonoxaline, etc.; and Q represents the non-metallic atoms required to complete a fused heterocyclic ring containing from 5 to 6 atoms in said ring, which ring may contain a second hetero atom such as oxygen, sulfur, selenium, or nitrogen, such as the following nuclei: a thiazole nucleus, e.g., thiazole, 4-methylthiazole, 4-phenylthiazole, S-methylthiazole, 5-phenylthiazo1e, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4-(2-thienyl)thiazole, benzothiazole, 4-chlorobenzothiazole, S-chlorobenzothiazole, 6-chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzthiazole, 5 methylbenzothiazole, 6 methylbenzothiazole, 5-bromobenzothiazole, 6-bromobenzothiazole, 6-phenylbenzothiazole, 5-phenylbenzothiazole, 4-methoxybenzothiazole, 5 methylbenzothiazole, 6 methylbenzothiazole, S-iodobenzothiazole, fi-iodobenzothiazole, 4-ethoxybenzothiazole, 5 ethoxybenzothiazole, tetrahydrobenzothiazole, 5,6 dimethoxybenzothiazole, 5,6 dioxymethylenebenzothiazole, 5 hydroxybenzothiazole, 6-hydroxybenzothiazole, naphtho[1,2-d]thiazole, naphtho[2,ld]thiazole, 5-methoxynaphtho[2,3-d]thiazole, 5 ethoxynaphtho[1,2-d]thiazole S-methoxynaphtho [2,1-d] thiazole, 7-methoxynaphtho [2,1-d] thiazole, 4' methoxythianaphtheno-7',6',4,5-thiazole, etc.; an oxazole ring, e.g., 4-methyloxazole, 5 methyloxazole, 4 phenyloxazole, 4,5 diphenyloxazole, 4 ethyloxazole, 4,5 dimethyloxazole, 5 phenyloxazole, benzoxazole, 5 chlorobenzoxazole, S-methylbenzoxazole, 5 phenylbenzoxazole, 6 methylbenzoxazole, 5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, 5 methoxybenzoxazole, 5 ethoxybenzoxazole, 5-chloronaphtho[2,1-d]oxazole, 6 methoxybenzoxazole, S-hydroxybenzoxazole, 6-hydroxybenzoxazo1e, naphtho- [2,1*d]oxazole, naphtho[1,2-d]oxazole, etc.; a selenazole ring, e.g., 4-methylselenazole, 4-phenylselenazole, benzoselenazole, 5 chlorobenzoselenazole, 5 methoxybenzoselenazole, 5-hydroxybenzoselenazole, tetrahydrobenzoselenazole, naphtho[2,1 d]selenazole, naphtho[1,2 d] selenazole, etc.; a thiazoline ring, e.g., thiazoline, 4-methylthiazoline, etc.; a pyridine ring, e.g., pyridine, 3-methylpyridine, 4-methylpyridine, etc.; a quinoline ring, e.g., quinoline, 3-methylquinoline, S-ethylquinoline, 6-ch1oroquinoline, 8-chloroquinoline, 6-methoxyquinoline, etc.; a 3,3-dialkylindolenine ring, e.g., 3,3-dimethylindolenine, 3,3-diethylindolenine, etc.; an imidazole ring, e.g., imidazole, l-alkylimidazole, 1-alkyl-4,S-dimethylimidazole, benzimidazole, l-alkylbenzimidazole, 1-aryl-5,6-dichlorobenzimidazole, l-alkyl-naphth 1,2-d] imidazole, l-arylnaphth[ 1,2-d1imidazole, l-alkyl-S-methoxy-naphth[1,2-d]

wherein m, L, R R and R are as previously defined; R represents an aryl group (e.g., phenyl, tolyl, xylyl, naphthyl, methoxyphenyl, cyanophenyl, nitrophenyl, chlorophenyl, etc.) and, Z represents the atoms required to complete a benzo group, which can be substituted.

Another highly useful class of the quaternated merocyanine dyes of the invention include those represented by the following general formula:

O=CO

Rs g e wherein m, L, R and R are as previously defined.

In accordance with another embodiment of this invention, novel quaternated merocyanine dyes are provided comprising first and second 5- to 6-membered nitrogen heterocyclic nuclei joined by a methine linkage; the first of said nuclei being selected from the group consisting of a 2-isoxazolin-5-one nucleus joined at the 4-carbon thereof to said linkage; a 2-pyrazolin-5-one nucleus joined at the 4-carbon atom thereof to said linkage, and a complex fused pyrimidinedione nucleus joined at the 3-carbon atom thereof to said linkage; and, said second nucleus being an electron-accepting nucleus joined at a carbon atom thereof to said linkage to complete said quaternated merocyanine dye. These novel dyes include those having For,- mula IV above, and those having Formulas 'I, II and III wherein Z represents the atoms required to complete an electron-accepting nucleus. Included among the electronaccepting nuclei are the nitro substituted thiazole, oxazole, selenazole, thiazoline, pyridine, quinoline, imidazole, imidazo[4,5-b1quinoxa1ine, 11 isoindolo[1,2 b]benzothiazole, Z-substituted indole, etc. Dyes containing such electron-accepting nuclei are the preferred spectral sensitizers for the organic photoconductor compositions and elements of this invention.

As used herein and in the appended claims, electron accepting nucleus refers to those nuclei which, when converted to a symmetrical carbocyanine dye and added to a gelatin silver chlorobromide emulsion containing 40 mole percent chloride and mole percent bromide, at a concentration of from 0.01 to 0.2 gram dye per mole of silver, cause by electron trapping at least about an percent loss in the 'blue speed of the emulsion when sensitometrically exposed and developed three minutes in Kodak developer D19 at 20 C., the composition of which is given above. Preferably, the electron-accepting nuclei are those, which, when converted to a symmetrical carbocyanine dye and tested as just described above, es sentially completely desensitize the test emulsion to blue radiation. Substantially complete desensitization as used herein, results in at least a percent, and preferably a percent loss of speed to blue radiation.

The quaternated merocyanine dyes of Formula I are prepared conveniently by heating a mixture of (1) a heterocyclic quaternary salt compound of the formula:

wherein n, R X and Z are as previously defined, and R represents an alkyl or aryl group, e.g., methyl, ethyl, phenyl, etc., and (2) a heterocyclic compound such as represented by the following formulas:

wherein L, R, R and R are as previously defined, in approximately equimolar proportions, in the presence of a condensing agent such as triethylamine, in an inert solvent such as ethanol. The crude dyes are separated from the reaction mixtures and purified by one or more recrystallizations from appropriate solvents. The purified dyes are then converted to the corresponding dye quaternary salts by heating them with conventional quaternizing reagents such as dimethyl sulfate, methyl p-toluenesulfonate, etc., followed by chilling and one or more recrystallizations.

Another convenient method for preparing many of the quaternated merocyanine dyes defined by Formulas I and II above comprises condensing (1) a heterocyclic compound of the formula:

wherein n, L, R X and Z are as previously defined, with (2) a heterocyclic compound defined by Formulas VII and VIII above, or a 3-aryl-Z-isoxazolin-S-one, or a 3- aryl-2-pyrazolin-5-one, in approximately equimolar proportions in the presence of a basic condensing agent such as triethylamine, in an inert solvent medium such as ethanol. The crude dyes obtained are separated and purified by one or more recrystallizations from appropriate solvents. The purified dyes are then quaternated by conventional methods such as described above and as set forth in the examples hereinafter.

The quaternated merocyanine dyes of the invention defined by Formula III above are conveniently prepared, for example, by condensing (1) a heterocyclic compound of the formula:

wherein 12, R X and Z are as previously defined, and R represents an alkyl group, e.g., methyl, ethyl, benzyl, etc., with (2) a heterocyclic compound of the formula:

wherein L and Q are as previously defined, in approximately equimolar proportions, in the presence of a basic condensing agent such as triethylamine, in an inert solvent medium. The crude dyes are separated and purified by one or more recrystallizations from appropriate solvents. The purified dyes are then quaternated by conventional methods such as previously described and as set forth in the examples hereinafter. For further details of preparing the intermediate unquaternated merocyanine dyes of this class, reference can be had to copending application of F. G. Webster, Ser. No. 639,024, filed May 17, 1967.

The quaternated merocyanine dyes of the invention such as defined by Formula IV above can be readily prepared by condensing (l) a heterocyclic compound of the formula:

wherein Z R and R are as previously defined, with (2) a 3-aryl-2-oxazolin-5-one, in approximately equimolar proportions, in a manner generally similar to the procedures described in the above methods, followed by converting the purified dye to a quaternated salt by conventional methods as described previously and as set forth in the example hereinafter.

The quaternated merocyanine dyes of the invention such as defined by Formula V above are readily prepared by condensing (1) a compound such as ll-isoindolo [1,2-b]benzothiazole carboxaldehyde with (2) a 3-aryl-2- 'isoxazolin-S-one, in approximately equimolar proportions, at elevated temperatures, and in an inert solvent medium such as acetic acid. The dye obtained is then quaternated by conventional methods such as previously described and as set forth in the examples hereinafter.

Further details for the preparation of the intermediate non-quaternated dye compounds can be had by reference to our copending application Ser. No. 666,513, filed Sept. 8, 1967, wherein such non-quaternated dyes and their preparations are described.

Included among the dyes defined by Formulas I to V above are the following typical dye compounds listed in Table A below. The general method herein for converting the starting non-quaternized dyes to the quaternary salt I RI*N(=CHCH)HI=C RY forms is illustrated with Dye No. 1.

TABLE A Dye N0. Compound I 1,3-diethy1-2-[(Z-methyl-fi-oxo-S-phenyl-3-isoxazolin-t-yhvinyl]imidazo[4,5 b]

quinoxalinium iodide. 1

C2115 11 if 00 C=OH -CI-I=C EBN-OH;

I Cs s I C2115 See footnote at end of table.

TABLE A-Continued Dye N0. Compound II. 3-eLh vl-2-[(2-methyl-5-oxo-3-phen yl-3-isoxazolin-4-yl) vinyl]-G- nitrobeuzothiazolium meth ylsulfate.

III l-methy1-3-l(2'methyl-5-0x0-3-phenyl-3-isoXazolin-4yl)inethylene]-2-phenyl- 3H-ind0lium iodide.

IV 2-[(2,3-dimethyl-fi-oxo-l-phenyl-Zi-pyrazolin4-yl) vinyl]-1,3-diethylimidazo [4,5-b1quinoxalinium iodide.

(32 H N N I Cu 5 *CHCII=C\ 9N-CH3 1 cm OSOzOMc C2I'I5 V 2-[ (2, 3-dimethyl-5bxo-1-phenyl-3-pyrazolini-yl) vinyl] -3-eth yl-(y nitrobenzothiazolium methylsuliate.

VI ll-l(Z-methyl-5'oxo-3-phenyl-3-isoxazolin-4-yl)-methylenelisoindolo[l,2-b]

benzothiazolium p-toluenesullonate.

O=CO CH=C GEN-CH3 N \C% S I C Il' e O S O 2 C 7H VII 3-ethyl-2-[(2-methyl-5-oxo-l-phenyl-3-pyrazolin-4 yl)-2-phenylvinyl] benzothiazoliuin p-toluenesulfonate.

VIII 1-ethyl-4-[(2-methyl-5-oxo-l-phenyl-3-pyrazolin-4-yl)-2-phenylvinyl] quinolinium p-tolueuesulionate.

IX l, 3,3-trirneth yl-2-[4-(2-methyl-5-oxo-Lphenyl-3-pyraz0linA-yl) -4-phenyl-l,

3-butadienyl]-2-indolinium iodide.

X 1,3,3-trimethyl-2-[(2-methyl-5-oxo-3-phenyl-3-isoxazoli114-yl)vinyl]-2- indolinium p-toluenesullonate.

XI 3-ethyl-2-[(2-methyl-5-oX0-3-phenyl-3-isoXazolin-4-yl)vinyl]benzothiazolium p-toluenesulfonate.

XII 3[(l,3-diethyl-2(1H)-imidazo[4,5-b]quinoxalinylidene) cthylidene]-3,4-dihyd10- 1-n1ethyl-2,4-dioxo'2H-pyrido[1,2-a]pyrimidinium iodide.

(IJ2 4 N N O=CN-CH 6B C: C H C H: O

XIII 3-[(l,3-diethyl-2(1H)-imidazo[4,5-b]quinoxalinylidene)ethylidene]-3,4

dihydro-1-rnethyl-2A-dioxo-2H-pyrimido[2,1-h]benzothiazolium iodide.

XIV S-ethylQ-[Q-meth yl-5-0xo-3-phenyl-3-isoxaZolin-4-yl) vinyl] -6 nitrobenzoxazolium methylsuliate.

XV 3-ethyl-2-[ (2-methyl-5-oxo-3-phenyl-3-isoxazolin4-yl) vinyl] -6- nitrobenzoselenazolium inethylsulfate.

quiuoxalinium iodide.

XVIL 2-[(2-allyl-l,3-dimethyl-5 oxo-3 pyrazolin-4-yl)-vinyl]-1,3-dimethyl-6- nitrobenzimidazolinium iodlde.

XVIII 3-[(1,3-diallyl-2 (II-I) -imidazo[4, 5-b]quinoxalinylideue) cthylidene1-1-allyl-3,

It will be understood that the above named dye compounds can be in any of the above defined quaternary salt forms, e.g., as the chloride, bromide, iodide, perchlorate, sulfamate, thiocyanate, p-toluenesulfonate, methyl sulfate, ethyl sulfate, etc. salts.

Dyes such as illustrated above can be used alone, or a combination of one or more of the above described dyes can be used to impart the desired spectral sensitivity. All of them are spectral sensitizers for organic photoconductors. Suitable organic photoconductors which are elfectively spectrally sensitized by such dyes include both monomeric and polymeric organic photoconductors. The invention is particularly useful in increasing the speed of organic photoconductors which are substantially insensitive, or which have low sensitivity (e.g., a speed less than 25 but generally less than 10 when tested as described in Examples 1 to 6 below) to radiation of 400 to 700 nm.

1 1 An especially useful class of organic photoconductors is referred to herein as organic amine photoconductors. Such organic photoconductors have as a common structural feature at least one amino group. Useful organic photoconductors which can be spectrally sensitized in acto about 1'2, and G represents a hydrogen atom, a mononuclear or polynuclear aromatic radical, either fused or linear (e.g., phenyl, naphthyl, biphenyl, etc.), a substituted aromatic radical wherein said substituent comprises an alkyl group, an a-lkoxy group, an acyl group, or a nitro cordance with this invention include, therefore, arylamine 5 group, or a poly(4'-vinylphenyl) group which is bonded compounds comprising 1) diarylamines, such as diphenylto the nitrogen atom by a carbon atom of the phenyl amine, i p y i p y group. Certain nitrogen heterocyclic compounds are also p y p y -P Y ph hyl m useful photoconductors in the invention such as, for ex- N,N'-diphenyl-p-phenylenediarnine; 2 carboxy-5-chlorol l 1,3,5-.tripher1yl-Z-pYIaZOline, 2,3,4,5 tetraphenyl- 4-methoxydiphenylamine; p anilinophenol; N,N di-2- pyrrole, etc. naphthyl-p-phenylene diamine; 4,4'-benzylidene-bis(N,N- Polyarylalkane photoconductors are particularly usediethyl-m-toluidine), those described in Fox US. Pat. ful in producing the present invention. Such photocon- 3,240,597 issued Mar. 15, 1966, and the like, and (2) triductors are described in US. Pat. 3,274,000; French Pat. arylamines including (a) nonpolymeric triarylamines, 1 1,383,461 and in a copending application of Seus et al. such as triphenylamine, N,N,N',N',tetraphenyl-m-phenyl- Ser. No. 624,233, Photoconductive Elements Containing enediamine; 4-acetyltriphenylamine, 4-hexanoyltriphenyl- Organic Photoconductors filed Mar. 20, 1967, now amine; 4-lauroyltriphenylamine; 4-hexyltriphenylamine, abandoned. These photoconductors include leucobases of 4-dodecyltryphenylamine, 4,4-bis(diphenylamino)-benzil, diaryl or triaryl methane dye salts, 1,1,1-triarylalkanes 4,4-bis(diphenylamino)-benzophenone, and the like, and wherein the alkane moiety has at least two carbon atoms (b) polymeric triarylamines such as poly[N,4"-(N,N',N'- and tetraarylmethanes, there being substituted an amine triphenylbcnzidine)]; polyadipyltriphenylamine, polysegroup on at least one of the aryl groups attached to the bacyltriphenylamine; polydecamethylenetriphenylamine; alkane and methane moieties of the latter two classes of poly-N-(4-vinylphenyl)-diphenylamine, poly N (vinylphotoconductors which are non-leuco base materials. phenyl)-a,a'dinaphthylamine and the like. Other useful Preferred polyaryl alkane photoconductors can be repamine-type photoconductors are disclosed in US. Pat. resented by the formula: 3,180,730, issued Apr. 27, 1965. D Other very useful photoconductive substances capable of being spectrally sensitized in accordance with this invention are disclosed in Fox US. Pat. 3,265,496 issued Aug. 9, 1966, and include those represented by the followmg general formula: wherein each of D, E and G is an aryl group and J is a hydrogen atom, an alkyl group, or an aryl group, at least I: l I one of D, E and G containing an amino substituent. The A b aryl groups attached to the central carbon atom are prefwherein A represents a mononuclear or polynuclear diembly phenyl g ps, although naphthyl groups can also valent aromatic radical, either fused or linear, (e.g., be used- Such aryl gTOPPS can cfmtam such Substltuems phenylene, naphthalene, biphenylene, binaphthalene, as alkyl and alkoxy typ cally havmg 1 to 8 carbon atoms, etc.), or a substituted divalent aromatic radical of these 40 hydroxy, In the h meta or Para PO51 ty-pes wherein said su'bstituent can comprise a member Hons ortho'substltuiefi phenyl bemg prefefred' The aryl Such as an acyl group having from 1 to about 6 carbon groups can also be oined together or cycllzed to form a atoms (6%, acetyl, propionyl ,butyryl, em), an alkyl fiuorene moiety, for example. The amino substituent can group having from 1 to about 6 carbon atoms (e.g., be presented by the formula methyl, ethyl, propyl, butyl, etc.), an alkoxy group having from 1 to about 6 carbon atoms (e.g., methoxy, ethoxy, propoxy, pentoxy, etc.), or a nitro group; A represents a mononuclear or polynuclear monovalent aro- R8 matic radical, either fused or linear (e.g., phenyl, naphthyl, biphenyl, etc.) or a substituted monovalent wherein each R can be an alkyl group typically having aromatic radical wherein said substituent can comprise 1 to 8 carbon atoms, a hydrogen atom, an aryl group, a member, such as an acyl group having from 1 to about or together the necessary atoms to form a heterocyclic 6 carbon atoms (e.g., acetyl, propionyl, butyryl, etc.), an amino group typically having 5 to 6 atoms in the ring alkyl group having from 1 to about 6 carbon atoms (e.g., such as morpholino, pyridyl, pyrryl, etc. At least one of methyl, ethyl, propyl, butyl, etc.), an a'lkoxy group hav- D, E and G is preferably p-dialkylaminophenyl group. ing from 1 to about 6 carbon atoms (e.g., methoxy, pro- When I is an alkyl group, such an alkyl group more genpoxy, pentoxy, etc.), or a nitro group; Q can represent a erally has 1 to 7 carbon atoms. hydrogen atom, a halogen atom or an aromatic amino Representative useful polyarylalkane photoconductors group, such as ANH; b represents an integer from 1 include the compounds listed below:

TABLE B grgmpound (1) 4,4-bis-(diethylarnjno)-2,2"dimethyltriphenylmethane. (2) .4,4"-diamino-4-dimethy1amino-2,2"-dimethytriphenylmethane. (3) 4,4-bis (dieth ylamino) -2 6-dichl0ro-2 ,2 -dimethyltriphenylmethane. (4) 4,4-b1s(d1ethylam1no)-2 ,2"-d1methyl(l1pheuylnaphthylmethane. (5) 2,2-dimethyl-4,4 ,4"-tris (dimethylamino) triphenylmethane.

. -4,4-bis(diethyla1nino) -4-dimethylamino-2 ,2"-dimethyltriphenylmethans. .4,4 bis(diethylamino)-2-ch1oro-2,2-dimethylt-dimethylaminotriphenylmethane. .4,4-bis(diethylamino) -4-dimethylamino-2,2,2"-trimethyltriphenylmethane.

4,4 -bis (dirnethylamino) -2-chloro-2 ,2 -dimethy1tiiphenylmethane.

,4-bis(dimethylan1ino) -2,2"-dimethyl-4-methoxytriph enylmethano. .4,4'-bis(benzylethyla.mjno) -2,2-dimethy1triphenylmethane.

4 4-bis(diethylamin0)-2,2'-diethoxytriphenylmethane.

4-bis (dimethylamlno) -1,1,1-triphenyloth ane. 1- (4-N,N-dimethylamjnophenyl) -1,1-diphenyletha11o. 4-dimethylaminotetraphenylmethane. 6) 4-diethylaminotetrapheuyhnethane.

As described herein a wide variety of photoconductor compounds can be spectrally sensitized with the dyes referred to above. Some organic photoconductors will, of course, be preferred to others; but in general useful results may be obtained from substantially all of the presently known organic photoconductors.

The following Table C comprises a partial listing of US. patents describing such organic photoconductors and compositions which can be used in place of those more particularly described herein.

Patent Inventor Issued Numbers Noe et a1 ..February 25, 1964.--. 3,122,435 Sus et a1 ....March 31, 1964 3, 127,266 Schlesinger. .April 21, 1964...- 130, 046 Cassiers .April 28, 1964.... 3, 131,060 June 30, 1964. 3,139,338 -.Do.--.-.-.- ,139,339 July 14, 1964 3,140,946 July 21, 1964 3, 141, 770 .September 15, 1964. 3, 148, 982 .November 3, 1964. ,155, 503 November 24, 1964 3, 158, 475 December 15, 1964. 3, 161 505 ecember 29, 1964.. 3 163, 530

"July 9, 1963..--...... ..November 26, 1963.-. 3, 11 .D ecember 3, 1963..- 3 Schlesinger. .December 17, 1963.. Kosche et al-... ..-.August 9, 1966 Noe et a1 ..September 20, 1966..-

Cassiers et al The spectrally sensitized organic photoconductor compositions of this invention can, in certain arrangements, be employed in electrophotographic elements in the absence of binder. For example, the photoconductor itself is sometimes capable of film formation, and therefore requires no separate binder. An example of such filmforming photoconductor is poly(vinylcarbazole). However, the more common arrangement is to provide a binder for the spectrally sensitized organic photoconductive materials. Any suitable binder material can be utilized for the spectrally sensitized organic photoconductors of the invention. Such binders should possess high dielectric strength, and have good insulating properties (at least in the absence of actinic radiation) as well as good film fonming properties. Preferred binder materials are polymers such as polystyrene, poly(methylstyrene), styrenebutadiene polymers, poly (vinyl chloride), poly- (vinylidene chloride), poly(vinyl acetate), vinyl acetatevinyl chloride polymers, poly(vinyl acetals), polyacrylic and methacrylic acid esters, polyesters such as poly (ethylene alkaryloxy-alkylene terephthalates), phenol-formaldehyde resins, polyamides, polycal'bonates and the like.

The photoconductive compositions of the invention can be coated on any of the electrically conductive supports conventionally used in electrophotographic processes, such as metal plates or foils, metal foils laminated to paper or plastic films, electrically conductive papers and films, papers and films coated with transparent electrically conductive resins and the like. Other useful conducting layers include thin layers of nickel coated by high vacuum deposition and cuprous iodide layers as described in US. Pat. 3,245,833. Transparent, translucent or opaque support material can be used. Exposure by reflex requires that the support transmit light while no such requirement is necessary for exposures by projection. Similarly transparent supports are desired if the reproduction is to be used for projection purposes; translucent supports are preferred for reflex prints; and opaque supports are adequate if the image is subsequently transferred by any means to another support, the reproduction is satisfactory as obtained, or the reproduction is to be used as a printing plate for preparing multiple copies of the original.

The quantity of the above-described dye required to spectrally sensitize an organic photoconductor varies with the results desired, the particular dye used, and the particular organic photoconductor used. Best results are obtained with about .01 to 10 parts by weight dye and about 1 to parts by weight of the organic photoconductor based on the photoconductive composition. Binder can be employed in such compositions, when desired, at preferred ranges of 25 to 99 parts by weight. In addition, the composition can contain other sensitizers, either spectral sensitizers or speed increasing compounds, or both.

As used herein and in the appended claims, the terms insulating and electrically conductive have reference to materials the surface resistivities of which are greater than 10 ohms per square unit (e.g., per square foot) and less than 10 ohms per square unit (e.g., per square foot) respectively.

Coating thicknesses of the photoconductive compositions of the invention on a support can vary widely. As a general guide, a dry coating in the range from about 1 to 200 microns is useful for the invention. The preferred range of dry coating thickness is in the range from about 3 to 50 microns.

To produce a reproduction of an image utilizing the electrophotographic elements of our invention, the photoconductive layer is preferably dark adapted, and then is charged either negatively or positively by means of, for example, a corona discharge device maintained at a potential of from 60007000 volts. The charged element is then exposed to light through a master, or by reflex in contact with a master, to obtain an electrostatic image corresponding to the master. This invisible image may then be rendered visible by being developed by contact with a developer including a carrier and toner. The carrier can be, for example, small glass or plastic balls, or iron powder. The toner can be, for example, a pigmented thermoplastic resin having a grain size of from about 1- 100p which may be fused to render the image permanent. Alternatively, the developer may contain a pigment or pigmented resin suspended in an insulating liquid which optionally may contain a resin in solution. If the polarity of the charge on the toner particles is opposite to that of the electrostatic latent image on the photoconductive element, a reproduction corresponding to the original is obtained. If, however, the polarity of the toner charge is the same as that of the electrostatic latent image, a reversal or negative of the original is obtained.

Although the development techniques described hereinabove produce a visible image directly on the electrophotographic element, it is also possible to transfer either the electrostatic latent image, or the developed image to a second support which may then be processed to obtain the final print. All of these development techniques are well known in the art and have been described in a number of US. and foreign patents.

This invention is further illustrated by the following examples.

EXAMPLES 1 AND 2 These examples show the great increase in speed of organic photoconductors when the dyes employed in this invention are added thereto. This increase in speed is due to the spectral sensitivity imparted to the photoconductor by the dyes described herein. The examples also show that the maximum sensitivity peaks (abs max.) occur in most cases at radiations in the region of the spectrum of from about 350 to 625 nm. A number of the dyes also have more than one maximum sensitivity peak as indicated in Table 1 hereinafter.

A series of solutions are prepared consisting of 5.0 ml. methylene chloride (solvent); 0.15 g. 4,4-bis(diethylamino)-2,2' dimethyltriphenylmethane (organic photoconductor); 0.50 g. polyester composed of terephthalic acid and a glycol mixture comprising a 9:1 weight ratio of 2,2 bis[4 (2-hydroxyethoxy)phenyl]propane and ethylene glycol (binder) and 0.0065 g. of the spectral sensitizing dye indicated by identifying number from above Table A. Each solution is coated on an aluminum tively, with maximum sensitivity peak at 485 nm., thus indicating a speed increase over that of the control by a factor of about 20 for the positively charged and about 14 for the negatively charged. Also of great significance is the extension of the absolute sensitivity to the region surface maintained at 25 C., and dried. All operations 5 of 485 nm. Even with the lower speed shown for the are carried out in a darkened room. A sample of each compositions and elements of the invention as illustrated coating is uniformly charged by means of a corona to a by Example 1 (Dye No. VI) the improvement in speed potential of about 600 volts and exposed through a transis impressive in comparison with that of the control by parent member bearing a pattern of varying optical denfactors of about 4.5 for both the positively charged and sity to a 3000 K. tungsten source. The resultant elecnegatively charged surfaces, respectively. Similar results trostatic image pattern is then rendered visible by cascadare obtained when dyes I-V, VII-XI and XIII-XVIII ing a developer composition comprising finely divided are substituted for dyes VI and XVII. colored thermoplastic electrostatically responsive toner Similar results to those shown in above Table I are obparticles carried on glass beads over the surface of the tained, when, for example, the organic photoconductor element. The image is then developed by deposition of 4,4-bis(diethylamino) 2,2 dimethyltriphenylmethane the toner in an imagewise manner on the element. is replaced with 0.15 g. of triphenylamine, (using the (Other development techniques such as those described p-toluenesulfonate salt of each dye), or 1,3,5-triphenyl-2- in US 2,786,439; 2,786,440; 2,786,441; 2,811,465; pyrazoline, or 2,3,4,5 tetraphenylpyrrole, or 4,4'-bis- 2,874,063; 2,984,163; 3,040,704; 3,117,884; Re. 25,779; diethylaminobenzophenone or when other dyes of the in- 2,297,691; 2,551,582; and in RCA Review, vol. 15 vention embraced by Formulas I to V above are used. (1954) pages 469-484, can be used with similar re- These results show that the dyes of this invention efsults.) An image is formed on each sample, as indicated fectively spectrally sensitize a wide variety of organic in Table I. Another sample of each coating is tested to photoconductors. The dyes of this invention are not in determine its electrical speed and maximum sensitivity themselves photoconductive. Also, it should be noted that peak. This is accomplished by giving each element a posithe above mentioned photoconductors when used alone tive or negative charge (as indicated in Table I) with a have very low photoconductive speed to visible light. Howcorona source until the surface potential, as measured ever, as shown by the tests, the combination of the dyes by an electrometer probe reaches 600 volts. It is then of the invention with the photoconductors of the invenexposed to light from a 3000 K. tungsten source of 20- tion provide compositions and elements of outstanding foot candle illuminance at the exposure surface. The exspeed and excellent quality of image. posure is made through a stepped density gray scale. The This invention is highly unexpected because dyes preexposure causes reduction of the surface potential of the viously suggested for spectral sensitizers impart weak element under each step of the gray scale from its initial spectral sensitization to organic photoconductors. Typipotential, V to some lower potential, V, whose exact cal dyes proposed by the prior art as spectral sensitizers, value depends on the actual amount of exposure in meterwhich produce weak spectral sensitization in these syscandle-seconds received by the area. The results of these terns, are shown in Table D below.

TABLE D Dye Identification Name A Pinacyanol.

B Krypto cyanine.

Anhydro-3-ethyl-9-methyl-3-(3-sulfobutyi)-thiacarbocyanine hydroxide. 3,3-diethyl-9-methylthiacarbocyanine bromide. 3-carboxymethyl-5-[(3-methyl-2-thiazolidiny1idene)-1-methylethylidenelrhodauine.

F "I. Anhydro5,5-dichlor0-3,9-diethy1-3-(3-sulfobutyl) thiacarbocyanine hydroxide. G 1-ethyl-3-mcthylthia-Z-cyanine chloride. H 1,1-diethyl-2,2-cyanine chloride.

TABLE I Shoulder Speeds Positively Negatively Sensitivity Example Dye Imago charged charged (Abs.max.) N o. No. formed surface surface nm.

Contr0l Nona.-. Yes"... 8 7 1 VI Yes-.. 36 32 470 2 XII... Yes-.. 160 100 485 Referring to the above Table I, it will be seen that the control example containing the same photoconductor but no dye shows speeds of only 8 and 7 for the positively and negatively charged surfaces, respectively, whereas the corresponding values for those of the invention represented by Examples 1 and 2 are clearly of a diiferent order of magnitude. For example, the highest speed is shown by Example 2 (Dye No. XII) of 160 and 100 for the positively and negatively charged surfaces, respec- In contrast, the dyes of this invention desensitize conventional negative type photographic silver halide emul- SlOllS.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove, and as defined in the appended claims.

We claim:

1. A composition of matter comprising an organic photoconductor spectrally sensitized with a quaternated merocyanine dye comprising first and second 5- to 6' membered nitrogen heterocyclic nuclei joined by a methine linkage; the first of said nuclei being selected from the group consisting of a 2-isoxazolin-5-one nucleus joined at the 4-carbon atom thereof to said linkage; a 2-pyrazolin-5-one nucleus joined at the 4-carbon atom thereof to said linkage, and a pyrimidinedione nucleus having attached to the 1- and 2-atoms thereof the nonmetallic atoms required to complete a ring containing from 5 to 6 atoms, said pyrimidinedione nucleus being joined at the 3-carbon atom thereof to said linkage.

2. A composition as defined in claim 1 wherein said second nucleus of said dye is an electron-accepting nucleus.

3. A composition as defined in claim 1 wherein said 17 second nucleus is an electron-accepting nucleus selected from the group consisting of a nitrobenzothiazole nucleus, a nitrobenzoxazole nucleus, a nitrobenzoselenazole nucleus, an imidazo[4,5-b]quinoxaline nucleus, a 1-alkyl-2- aryl-3H-indole nucleus and an 11-isoindolo[1,2-b]benzo thiazole nucleus.

4. A composition of matter comprising an organic photoconductor spectrally sensitized with a quaternated merocyanine dye selected from those represented by the following formulas:

wherein n and In each represents a positive integer of from 1 to 2; L represents a methine linkage; R and R each represents a member selected from the group consisting of an alkyl group, and an alkenyl group; R represents a member selected from the group consisting of a hydrogen atom, an alkyl group and an aryl group, R and R each represents a member selected from the group consisting of an alkyl group and an aryl group; R represents an aryl group; X represents an acid anion; Z represents the non-metallic atoms required to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring; Q represents the non-metallic atoms required to complete a fused heterocyclic ring containing from 5 to 6 atoms in said ring; and, Z represents the atoms required to complete a benzo group.

5. A composition as defined in claim 4 wherein said Z of said dye represents the non-metallic atoms required to complete an electron-accepting nucleus.

6. A composition as defined in claim 4 wherein said Z represents the non-metallic atoms required to complete an electron-accepting nucleus selected from the group consisting of a nitrobenzothiazole nucleus, a nitrobenzoxazole nucleus, a nitrobenzoselenazole nucleus and an imidazo- [4,5 -b] quinoxaline nucleus.

7. A composition as defined in claim 4 wherein said Q of said dye represents the non-metallic atoms required to complete a fused heterocyclic ring selected from the group consisting of a thiazole ring, an oxazole ring, a selenazole ring, a thiazoline ring, a pyridine ring, a quinoline ring, a 3,3-dialkylindolenine ring and an imidazole ring.

18 8. A composition as defined by claim 4 wherein said organic photoconductor has the following formula:

wherein each of D, E and G is an aryl group and J is selected from the group consisting of a hydrogen atom, an alkyl group and an aryl group, at least one of D, E and G containing an amino substituent selected from the group consisting of a secondary amino group and a tertiary amino group.

9. A composition as defined by claim 4'wherein said organic photoconductor is selected from the group consisting of: triphenylamine; 1,3,S-triphenyl-Z-pyrazoline; 4,4 bis(diethylamino) 2,2 dimethyltriphenylamine; 2,3,4,5 tetraphenylpyrrole; and 4,4 bis diethylaminobenzophenone.

10. A composition as defined by claim 4 wherein said photoconductor comprises from 1 to 75 parts by weight of said composition, said photoconductor being spectrally sensitized with from .01 to 10 parts by weight of said composition of said dye.

11. A composition as defined by claim 4 wherein said organic photoconductor and said dye are incorporated in an insulating binder.

12. A composition as defined by claim 4 wherein said organic photoconductor and said dye are dispersed in from 25 to 99 parts by weight of a polyester of terephthalic acid and a glycol mixture consisting of a 9:1 weight ratio of 2,2-bis-[4-(2-hydroxyethoxy)phenyl]-propane and ethylene glycol as insulating binder.

13. A composition of matter comprising from 1 to 75 parts by weight of an organic photoconductor selected from the group consisting of: triphenylamine; 1,3,5-triphenyl 2 pyrazoline; 4,4 bis diethylamino-2,2'-dimethyltriphenylmethane; 2,3,4,5-tetraphenylpyrrole; 4,4- bis-diethylaminobenzophenone; said organic photoconductor being spectrally sensitized with from .01 to 10 parts by weight of a dye selected from the group consisting of a 2-[(2,3-dimethyl-5-oxo-1-phenyl-3-pyrazolin-4- yl)vinyl] 3 ethyl 6 nitrobenzothiazolium salt; a 11 [(2 methyl 5 oxo 3 phenyl-3-isoxazolin-4-yl) methylene]isoindolo[1,2-b]-benzoihiazolium salt and a 3 [(1,3 diethyl 2(1H)-imidat:o[4,5-b]-quinoxalinylidene)ethylidene] 3,4 dihydro l methyl-2,4-dioxo- 2H-pyrido[1,2-a]pyrimidinium salt.

14. A composition of matter as iefined in claim 13 wherein said organic photoconductor and said dye are incorporated in an insulating binder.

15. A composition of matter as defined in claim 13 wherein said organic photoconductor and said dye are dispersed in from 25 to 99 parts by weight of a polyester of terephthalic acid and a glycol mixture consisting of a 9:1 weight ratio of 2,2 bis[4 (2 hydroxyethoxy)-phenyl]- propane and ethylene glycol as inulating binder.

16. An electrophotographic element comprising a conductive support having thereon a layer comprising an organic photoconductor in an insulating binderv said organic photoconductor being spectrally sensitized with a cyanine dye selected from those comprising first and second 5- to 6-membered nitrogen containing heterocyclic nuclei joined together by a methine linkage; said first nucleus being selected from the group consisting of a 2-isoxaizolin-5-one nucleus joined at the 4-carbon atom thereof to said linkage; a 2-pyrazolin-5-one nucleus joined at the 4-carbon atom thereof to said linkage, and a pyrimidinedione nucleus having attached to the 1- and 2-atoms thereof the non-metallic atoms required to complete a ring containing from 5 to 6 atoms, said pyrimidinedione nucleus being joined at the 3-carbon atom thereof to said linkage.

17. An electrophotographic element comprising a conductive support having thereon a layer comprising an organic photoconductor spectrally sensitized with a quaternated merocyanine dye selected from those represented by the following formulas:

wherein n and m each represents a positive integer of from 1 to 2; L represents a methine linkage; R and R each represents a member selected from the group consisting of an alkyl group, and an alkenyl group; R represents a member selected from the group consisting of a hydrogen atom, an alkyl group and an aryl group, R and R each represents a member selected from the group consisting of an alkyl group and an aryl group; R represents an aryl group; X represents an acid anion; Z represents the non-metallic atoms required to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring; Q represents the non-metallic atoms required to complete a fused heterocyclic ring containing from 5 to 6 atoms in said ring; and, Z represents the atoms required to complete a benzo group.

18. An electrophotographic element as defined in claim 17 wherein said Z of said dye represents the non-metallic atoms required to complete an electron-accepting nucleus.

19. An electrophotographic element as defined in claim 17 wherein said Z represents the non-metallic atoms required to complete an electron-accepting nucleus selected from the group consisting of a nitrobenzothiazole nucleus, a nitrobenzoxazole nucleus, a nitrobenzoselenazole nucleus and an imidazo [4,5-b]quinoxaline nucleus.

20. An electrophotographic element as defined in claim 17 wherein said Q of said dye represents the non-metallic 20 atoms required to complete a fused heterocyclic ring selected from the group consisting of a thiazole ring, an oxazole ring, a selenazole ring, a thiazoline ring, a pyridine ring, a quinoline ring, a 3,3-dialky1indolenine ring and an imidazole ring.

21. An electrophotographic element as defined in claim 17 wherein said organic photoconductor has the following formula:

1 wherein each of D, E and G is an aryl group and J is selected from the group consisting of a hydrogen atom, an alkyl group and an aryl group, at least one of D, E and G containing an amino substituent selected from the group consisting of a secondary amino group and a tertiary amino group.

22. An electrophotographic element as defined in claim 17 wherein said organic photoconductor is selected from the group consisting of: triphenylamine; 1,3,5-triphenyl- 2-pyrazoline; 4,4 bis (diethylamino)-2,2'-dimethy1- triphenylamine; 2,3,4,5-tetraphenylpyrrole; and '4,4-bisdiethylaminobenzophenone.

23. An electrophotographic element as defined in claim 17 wherein said organic photoconductor and said dye are incorporated in an insulating binder.

24. An electrophotographic element as defined in claim 17 wherein said organic photoconductor and said dye are dispersed in from 25 to 99 parts by weight of a polyester of terepht halic acid and a glycol mixture consisting of a 9:1 weight ratio of 2,2-bis-[4-(2-hydroxyethoxy)-phenyl]- propane and ethylene glycol as insulating binder.

25. An electrophotographic element comprising a conductive support having thereon a layer comprising from 1 to parts by weight of an organic photoconductor selected from the group consisting of: triphenylamine; 1,3,5- triphenyl-Z-pyrazoline; 4,4'-bis-diethylamino 2,2 dimethyltriphenylmefihane; 2,3,4,5-tetraphenylpyrrole; 4,4- bis-diethylaminobenzophenone; said organic photoconductor being spectrally sensitized with from .01 to 10 parts by weight of a dye selected from the group consist ing of 11-[(Z-methyl-5-oXo-3-phenyl-3-isoXazolin-4-yl)- methylene]isoindolo[1,2-b]benzothiazolium salt and a 3- [(1,3-diethy1 2(1H) imidazo[4,5-b]quinoxalinylidene) ethylidene]-3,4-dihydro 1 methyl-2,4,dioxo-ZH-pyrido- 1,2-a1pyrimidinium salt.

References Cited UNITED STATES PATENTS 2,454,629 11/1948 Brooker 96-105X 2,656,352 10/1953 Knott et a1. 96105X 3,110,591 11/1963 Stewart 96-1.7 3,174,854 3/1965 'Sturnpf et al. 96-1.5 3,265,496 8/1966 Fox 961.5 3,279,918 10/1966 Cassiers et a1. 961.5 3,287,120 11/1966 Hoegl 961.5

CHARLES E. VAN HORN, Primary Examiner U.S. Cl. X.R. 961.5; 260-2404 

